Conventional wisdom around the backyard
biodiesel folks in my area says that
the IDIs all need their rubber fuel lines replaced,
and TDIs are do not.
Also, they say that it wont fail catastrophically,
but begin to weep after a period of time.
I went through some stress to find Viton - insert fuel lines,
in hopes that I will one day have it on bio.
I found a local hose company who sold me 5/16" viton-insert
B100 compatible fuel hose for like $6-7 per foot.
I was unable to find the smaller sizes needed for the return line, though
(Both Injector return lines, and return from pump to body lines)
There are plenty of places online selling B100-comp fuel hose kits for IDI,
IIRC $100-140.
-Brad